Sustainable RCCI engine operation with an ANN based novel tri-fuel approach

This research delves into a novel tri-fuel RCCI engine strategy that uses diesel as the base fuel, biodiesel from Andropogon narudus, and hydrogen as a reactivity promoter to enhance combustion efficiency and enhance environmental sustainability. The tested blends, BD80H20 and BD70H30, showed a 3-5% improvement in Brake Thermal Efficiency (BTE) compared to conventional diesel at full load operation. Hydrogen-rich blends recorded a 5-8% brake-specific fuel economy improvement over diesel and B20 at both 75% and 100% engine loads. The biodiesel has made a substantial reduction in hydrocarbon (HC) and carbon monoxide (CO) emissions. Specifically, B20 recorded a 15% decrease in HC and 12% decrease in CO emission compared to straight diesel, while hydrogen blends register another decrease of 20-25% in CO emissions. The addition of hydrogen resulted in a rough estimate of 10-15% increase in the emissions of carbon dioxide (CO₂) and nitrogen oxides (NOx), reflecting an emission trade-off. The smoke opacity decrease varied between 18 and 25% for hydrogen-biodiesel blends, reflecting an increased combustion efficiency level. The increase in in-cylinder peak pressure by 5-10% with hydrogen reflects an accelerated and efficient combustion process. A sustainability analysis by means of a Pugh matrix and Kiviat plot showed that BD80H20 was the most sustainable mixture. The ANN validation proved to be of excellent prediction quality, with RMSE values ranging from 0.9965 to 0.9996, and MPAE less than 4%.